Metal‐Templated Macrolactamization of Triamino and Tetramino Esters. Facile Synthesis of Macrocyclic Spermidine and Spermine Alkaloids, (S)‐(+)‐Dihydroperiphylline, (.+‐.)‐Buchnerine, (.+‐.)‐Verbacine, (.+‐.)‐Verbaskine, and (.+‐.)‐Verbascenine.